2002 NEC for fire pumps
2002 NEC for fire pumps
(OP)
Hey guys,
In the new NEC, it states in section 695.4B, that overcurrent protection between a standby gen. and fire pump controller shall be selected to provide short circuit protection only. Does this imply that one could use an MCP to protect the circuit from short circuit events?
In the new NEC, it states in section 695.4B, that overcurrent protection between a standby gen. and fire pump controller shall be selected to provide short circuit protection only. Does this imply that one could use an MCP to protect the circuit from short circuit events?






RE: 2002 NEC for fire pumps
RE: 2002 NEC for fire pumps
I agree with what you're saying, but don't a lot of the combination fire pump controllers/automatic transfer switches have motor starters in them, which would allow the use of an MCP?
RE: 2002 NEC for fire pumps
If you make any changes to a listed controller, you no longer have a UL-listed device.
You cannot use an MCP as a stand-alone device to protect anything. It might not be logical, but I don't believe the NEC allows that under circumstances.
RE: 2002 NEC for fire pumps
For example: It may be acceptable to run a 100 Amp feeder from a 400A braker
RE: 2002 NEC for fire pumps
The reasoning behind this statement in the code is that it's preferable to let the fire pump and/or generator run overloaded -- even until one of them stops due to overheating -- rather than stop supplying fire water to the sprinklers & standpipes while a fire is in progress. Sacrifice a machine to possibly save lives and property.
Thus, no overloads are permitted. A magnetic-only instantaneous trip breaker sized to the maximum allowed for the motor horsepower and voltage in question is the answer, and this is basically what an MCP is. However, you'd need to find one enclosed and listed as an assembly to meet the listing requirements. Talk to your favorite circuit breaker rep, I bet they have just the ticket already made up for you.
Best of luck!
Old Dave
RE: 2002 NEC for fire pumps
That's what I was thinking. I appreciate it...
Mike
RE: 2002 NEC for fire pumps
The fire pump supply is generally tapped directly from the service entrance conductors ahead of the main service disconnecting means. If you run this tap outside the building, you can run it directly to the fire pump controller without an additional breaker. The fire pump controller is the service disconnect for the fire pump.
If you do install an additional breaker at the tap, I still think you will end up using a thermal-mag (or electronic) trip. It will have to be sized to carry the locked-rotor current of the fire pump motor, so it would end up being oversized, as would the conductors. But I've been wrong before.
If you have a special situation, I'd suggest discussing with local electrical inspector and the fire marshall before buying any equipment.
RE: 2002 NEC for fire pumps
RE: 2002 NEC for fire pumps